Customs VAT on Purchase Order

Hi

When my client receives an invoice from a shipping company for imported goods, there is a separate line charging for Customs VAT (Value-added Tax). When creating the Purchase Order, how can I enter this line as a full VAT amount, in order for the whole amount to be only included in my VAT total for the Purchase Order.

In other words, I want to be able to enter a line on the PO which is just VAT and in turn will be going to the appropriate VAT Control account.

Is this possible or any way of handling such charges?

Thank you

Sean